Pyrotechnic mixture manufacture

The term "pyrotechnics" is defined in the Explosive Control Law in Japan as those items manufactured with propellants or explosives to meet a certain purpose 5). The materials having pyrotechnical effects are called pyrotechnics in general. Pyrotechnical effects refer to the emission of heat, light, flame, sound, gas or smoke. The terms "pyrotechnic compositions" or "pyrotechnic mixtures" are broadly used. These terms refer to the raw materials for the production of pyrotechnics. Recommendations on the Transport of Dangerous Goods of United Nations c defines "pyrotechnic substance" as follows ... 

The roasted clinker is then leached out with hot water and the resulting liquor filtered to remove insoluble silica, along with aluminum and iron oxides present as impurities in the original chromite ore. Pure sodium dichromate is then crystallized and dried. The anhydrous sodium chromate can then be reduced to chromium trioxide by simple carbothermic reduction. Note that the sodium chromate produced can be converted into the dichromate by dissolving it in sulfuric acid and is the basis for the manufacture of all industrially important chromium chemicals. Once produced, chromium trioxide is mixed with aluminum powder and lime and placed inside a refractory-lined steel vessel. The exothermic reaction is started by igniting a pyrotechnic mixture made of barium peroxide and aluminum powder or potassium chlorate aluminum powder ... 

Possible Areas Where Variation in the Performance and Sensitivity of Pyrotechnic Mixtures Can Occur During the Manufacturing Process... 

Potassium chlorate is used mainly in the manufacture of matches (qv) and pharmaceutical preparation. In pyrotechnics, chlorate salts may be mixed with certain organic compounds such as lactose to give a relatively cool flame, so that certain dyes may be incorporated in the mixture to give colored flares. 

The famous Chinese firecracker uses a mixture of potassium chlorate, sulfur, and aluminum. The chlorate combined with sulfur makes this mixture doubly dangerous for the manufacturer. The ignition temperature of the potassium chlorate/sulfur system is less than 200°C The presence of aluminum - an excellent fuel - guarantees that the pyrotechnic reaction will rapidly propagate once it begins. Safety data from China is unavailable, but one has to wonder how many accidents occur annually from the preparation of this firecracker composition. The preparation of potassium chlorate/sulfur compositions was banned in Great Britain in 1894 because of the numerous accidents associated with this mixture ... 

Most explosive and pyrotechnic reactions produce significant quantities of smoke, and this visible phenomenon may or may not be desirable. Smoke can obscure colored flames, and therefore attempts are made to keep the production of smoke to a minimum in such mixtures. However, a variety of smoke-producing compositions are purposefully manufactured for use in daytime signalling and troop and equipment obscuration, as well as for amusement and entertainment purposes. 

This comprises substances, mixtures and articles which are manufactured with a view to producing a practical, explosive or pyrotechnic effect. 

Use Fertilizer, explosives especially as prills/oil mixture, pyrotechnics, herbicides and insecticides, manufacture of nitrous oxide, absorbent for nitrogen oxides, ingredient of freezing mixtures, oxidizer in solid rocket propellants, nutrient for antibiotics and yeast, catalyst. 

The manufacture of the phosphorus match, the first pyrotechnic match, began industrially in Germany in 1832. It had a mixture of white phosphorus and sodium chlorate as match-head and was inflammable on striking against anything, the boots for instance. This obviously created a risk of fire. The white phosphorus was in addition a poisoning risk. This type of match was banned at the beginning of the 20 century. 

Much of pyrotechnic reactivity is related to the particle sizes of the components of a given composition. Perhaps the first piece of eqnipment that is purchased should be a particle size analyzer for the determination of particle size, and particle size distribution, in starting chanicals to be used to manufacture energetic mixtures. This can be as simple as a set of sieves and a shaker apparatus, or can be a more elaborate (and expensive) piece of instrumentation (see Chapter 4). 

Spark sensitivity values for a series of pyrotechnic compositions are given in Table 6.1. It can be seen that these values tend to be considerably greater than 0.10 J, unless a line metal powder (such as aluminum) is used. Keep in mind that spark sensitivities can vary greatly for a given oxidizer-fuel mixture, with the particle size and surface oxidation state of the fuel often playing a very significant role. A manufacturer cannot rely on spark sensitivity results other than those obtained on compositions produced by his company. 

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